Another American medical missionary has Ebola

A man reads an Ebola warning on a van door in Monrovia, Liberia. (AP Photo/Abbas Dulleh)

An American doctor working in West Africa has tested positive for the Ebola virus, a missionary group announced on Tuesday.

The unidentifed doctor is the third U.S. medical missionary to contract the deadly disease in the past six weeks.

SIM USA, an international Christian aid organization, said the doctor was treating obstetrics patients at the group’s hospital in Monrovia, Liberia, when he felt Ebola symptoms and immediately quarantined himself.

The group said the doctor has since been transferred to an Ebola isolation unit and is “doing well and is in good spirits.”

The group, based in Charlotte, North Carolina, didn’t reveal the doctor’s age or how long he had been working in West Africa. It said specifics on how the doctor contracted the virus haven’t been determined.

Two American medical missionaries contracted Ebola in Monrovia in late July and were eventually evacuated to an Atlanta hospital, marking the first time a patient with a known case has been treated in the United States.

The Ebola outbreak in West Africa has been described as the worst ever. More than 1,550 people have died since it was first reported in the forests of southeastern Guinea in March.

The international group Doctors Without Borders warned on Tuesday that the world is losing the battle against Ebola, The Associated Press reported. The organization called on other countries to contribute civilian and military medical personnel familiar with biological disasters.

“My heart was deeply saddened, but my faith was not shaken, when I learned another of our missionary doctors contracted Ebola,” Bruce Johnson, president of SIM USA, said in a written statement. “As a global mission, we are surrounding our missionary with prayer, as well as our Liberian SIM/ELWA colleagues, who continue fighting the Ebola epidemic in Liberia. We have gifted Liberian doctors, medical staff and support staff who are carrying on the fight.”

SIM USA will hold a news conference Wednesday afternoon to provide more details.

There is no treatment or vaccine for Ebola, but health officials say it can be contained if the sick are immediately quarantined and vigilant sanitation practices are followed. The virus has been known to kill up to 90 percent of those infected.